Biofilm Formation, Attachment, and Cell Hydrophobicity of Foodborne Pathogens under Varied Environmental Conditions

Biofilm formation, attachment and cell hydrophobicity of foodborne pathogens, including Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus were investigated under various environmental conditions such as sodium chloride (0.5-7.0%, w/v), glucose (0.25-10.0%, w/v), pH (6.0-6.8), temperature (25 and 37 degrees C), incubation time (24 and 6 h), and nutrients trypic soy broth (TSB) and diluted TSB (1:10). Biofilm formation for 24 h at 25 and 37 degrees C and attachment for 30 min and 6 h on the surface of polystyrene were measured by the crystal violet staining method. Cell hydrophobicity of pathogens for 6 and 24 h at 25 and 37 degrees C was conducted using the modified bacterial adherence to hydrocarbons method (mBATH). Biofilm formation and attachment of pathogens were highly influenced by the addition of glucose and sodium chloride compared to pH. The biofilm of all pathogens formed in TSB was greater than that in diluted TSB. Biofilm formations of S. aureus and P aeruginosa at 37 degrees C were greater than that at 25 degrees C. However, biofilm formation of L. monocytogenes was not significantly affected by temperature. Levels of L. monocytogenes hydrophobicity were influenced by adding glucose and sodium chloride at 37 degrees C, whereas levels of hydrophobicity for other pathogens were significantly different depending on the glucose condition (p <0.05). The results demonstrate that biofilm formation, attachment, and hydrophobicity of pathogens were affected by environmental conditions such as the addition of glucose and sodium chloride. However, factors affecting biofilm formation and cell hydrophobicity differed depending on the pathogen type.